SQL Server on Azure VMs

Cost and performance is likely going to be your key considerations when placing your SQL Server on Azure.

Microsoft provides the following Performance guidelines for SQL Server in Azure Virtual Machines and SQL server best practices to optimize performance in Azure Stack documents which give a comprehensive overview of configuring SQL Server on Azure VMs.

As I’ve been working quite a bit on Azure lately, I thought I’d list a few of my findings.

Picking a Virtual Machine

At the time of this blog, there were 172 VM sizes to choose from.

172 VM sizes

The key considerations for a SQL Server VM relate to:

  • CPUs (Potentially impacts license costs)
  • Memory (The more memory the better as much faster than disk)
  • Disk capacity (Sufficient disks space to store your databases/backups)
  • Disk speed (Impacts data read/write access performance)

So with this in mind we can narrow down suitable VMs.

If the goal is to get a SQL Server 2017 Standard Edition VM with 4 vCPUs (minimum core license requirement) and 128GB RAM (Edition limit) we end up with a E16-4s_v3.

SQL Server 2017 Standard Edition VM option with 128GB Ram

The E16-4s_v3 is a constrained core size VM (see below) which has 4 vCPUs, 128GB memory and up to 25,600 IOPS.

Constrained core size VMs allow for a reduced vCPU count for licensing while keeping the RAM and MAX IOPS unchanged for the same price.

Constrained core size VMs for E16s_v3

In Microsoft’s documentation they refer to use of DS2_v2 or higher for Standard Edition and DS3_v2 or higher for Enterprise Edition.

DS VMs

If the goal is to obtain a VM with maximum disk IOPS (currently 80,000) while keeping SQL license costs down you’ll probably be best to go with a E64-16s_v3 which has 16 vCPUs and 432GB RAM.

VMs which allow up to 80,000 IOPS

VM Disks

Once you have decided on your VM, the next most important step is deciding on the disks to add to the VM.

Premium SSD disks available

The table above shows the max throughput available for the disk, but depending on your VM you may not achieve that throughput due to Microsoft setting IOPS limits on the various VMs.

I’ll demonstrate these limits with the widely used CrystalDiskMark tool to place load on various disk configurations.

Below shows CrystalDiskMark run against a very old $100 Apacer AS681 SSD 2.5 7mm SATAIII, 240GB drive which is no longer sold.

Example

All tests were run 3 times using a 1GB file to save time.

  • Seq Q32T1: Sequential, Queues = 32, Threads = 1
  • 4KiB Q8T8: Random 4KiB, Queues = 8, Threads = 8
  • 4KiB Q32T1: Random 4KiB, Queues = 32, Threads = 1
  • 4KiB Q1T1: Random 4KiB, Queues = 1, Threads = 1

All tests made use of the recommended Storage Spaces with Simple Resiliency and the number Columns (think of it as a stripe) equaling the number of disks. The disks were formatted using best practice NTFS 64K allocation unit size and GPT partition to allow exceeding 2TB. Simple Resiliency is all that is required due to the underlying Azure infrastructure ref: “Locally redundant storage (LRS) replicates your data three times within a single data center. LRS provides at least 99.999999999% (11 nines) durability of objects over a given year.”

  • E16-4s_v3: Has 4 vCPUs, 128GB RAM and Max IOPS 25,600
  • E32-8s_v3: Has 8 vCPUs, 256GB RAM and Max IOPS 51,200
  • E64-16s_v3: Has 16 vCPUs, 432GB RAM and Max IOPS 80,000

Host Caching set to None

  E16-4s_v3 E32-8s_v3 E64-16s_v3
  Read / Write (MB/s) Read / Write (MB/s) Read / Write (MB/s)
1 x P30: Seq Q32T1 204 / 205 204 / 206 204 / 206
1 x P30: 4KiB Q8T8 21 / 20 20 / 20 20 / 21
1 x P30: 4KiB Q32T1 21 / 21 20 / 20 21 /21
1 x P30: 4KiB Q1T1 1 / 1 1 / 1 1 /1
Cost per month NZ$ 204.37 (Size 1TB)
       
2 x P30: Seq Q32T1 395 / 393 411 / 409 411 / 409
2 x P30: 4KiB Q8T8 41 / 41 41 / 41 41 / 41
2 x P30: 4KiB Q32T1 40 / 40 38 / 39 39 / 40
2 x P30: 4KiB Q1T1 1 / 1 1 / 1 1 / 1
Cost per month NZ$ 408.74 (Size 2TB)
       
3 x P30: Seq Q32T1 392 / 393 613 / 612 612 / 612
3 x P30: 4KiB Q8T8 61 / 62 61 / 62 61 / 62
3 x P30: 4KiB Q32T1 41 / 47 40 / 43 41 / 45
3 x P30: 4KiB Q1T1 1 / 1 1 / 1 1 / 1
Cost per month NZ$ 613.11 (Size 3TB)
       
4 x P30: Seq Q32T1 394 / 394 783 / 780 815 / 811
4 x P30: 4KiB Q8T8 80 / 81 80 / 81 80 / 81
4 x P30: 4KiB Q32T1 42 / 47 42 / 45 42 / 45
4 x P30: 4KiB Q1T1 1 / 1 1 / 1 1 / 1
Cost per month NZ$ 817.48 (Size 4TB)
       
5 x P30: Seq Q32T1 392 / 394 783 / 778 1006 / 896
5 x P30: 4KiB Q8T8 84 / 97 83 / 88 87 / 93
5 x P30: 4KiB Q32T1 42 / 47 41 / 45 42 / 45
5 x P30: 4KiB Q1T1 1 / 1 1 / 1 1 / 1
Cost per month NZ$ 1,021.85 (Size 5TB)
       
1 x P40: Seq Q32T1 255 / 257 257 / 256 255 / 257
1 x P40: 4KiB Q8T8 31 / 31 31 / 31 31 / 31
1 x P40: 4KiB Q32T1 31 / 31 31 / 31 31 / 31
1 x P40: 4KiB Q1T1 1 / 1 1 / 1 1 / 1
Cost per month NZ$ 391.67 (Size 2TB)
       
1 x P60: Seq Q32T1 392 / 394 513 / 511 510 / 511
1 x P60: 4KiB Q8T8 66 / 67 66 / 67 66 / 67
1 x P60: 4KiB Q32T1 51 / 59 46 / 51 46 / 54
1 x P60: 4KiB Q1T1 1 / 1 1 / 1 1 / 1
Cost per month NZ$ 1,430.42 (Size 8TB)
       
1 x P70: Seq Q32T1 393 / 394 765 / 764 766 / 764
1 x P70: 4KiB Q8T8 75 / 75 75 / 75 75 / 75
1 x P70: 4KiB Q32T1 51 / 58 46 / 52 45 / 59
1 x P70: 4KiB Q1T1 1 / 1 1 / 1 1 / 1
Cost per month NZ$ 2,724.62 (Size 16TB)

As shown above, there is clearly VM throttling in place and you could possibly be throwing money away by trying to use faster and/or more disks to get better IO performance.

Host Caching set to Read-only

  E16-4s_v3 E32-8s_v3 E64-16s_v3
  Read / Write (MB/s) Read / Write (MB/s) Read / Write (MB/s)
1 x P30: Seq Q32T1 269 / 205 538 / 205 1073 / 206
1 x P30: 4KiB Q8T8 133 / 21 268 / 21 534 / 20
1 x P30: 4KiB Q32T1 134 / 21 269 / 21 470 / 21
1 x P30: 4KiB Q1T1 19 / 1 54 / 1 58 / 1
Cost per month NZ$ 204.37 (Size 1TB)
       
2 x P30: Seq Q32T1 269 / 268 536 / 408 1071 / 408
2 x P30: 4KiB Q8T8 134 / 41 269 / 41 535 / 41
2 x P30: 4KiB Q32T1 134 / 38 269 / 39 489 / 40
2 x P30: 4KiB Q1T1 20 / 1 54 / 1 61 / 1
Cost per month NZ$ 408.74 (Size 2TB)
       
3 x P30: Seq Q32T1 269 / 268 539 / 535 1075 / 611
3 x P30: 4KiB Q8T8 134 / 61 267 / 61 535 / 62
3 x P30: 4KiB Q32T1 134 / 35 268 / 42 463 / 44
3 x P30: 4KiB Q1T1 19 / 1 54 / 1 58 / 1
Cost per month NZ$ 613.11 (Size 3TB)
       
4 x P30: Seq Q32T1 270 / 269 540 / 535 1073 / 812
4 x P30: 4KiB Q8T8 134 / 72 267 / 81 536 / 81
4 x P30: 4KiB Q32T1 134 / 37 268 / 44 481 / 44
4 x P30: 4KiB Q1T1 20 / 1 52 / 1 60 / 1
Cost per month NZ$ 817.48 (Size 4TB)
       
5 x P30: Seq Q32T1 268 / 270 538 / 535 1074 / 877
5 x P30: 4KiB Q8T8 134 / 66 269 / 89 535 / 90
5 x P30: 4KiB Q32T1 134 / 36 268 / 45 477 / 46
5 x P30: 4KiB Q1T1 18 / 1 54 / 1 60 / 1
Cost per month NZ$ 1,021.85 (Size 5TB)
       
1 x P40: Seq Q32T1 269 / 256 540 / 256 1075 / 256
1 x P40: 4KiB Q8T8 134 / 31 270 / 31 535 / 31
1 x P40: 4KiB Q32T1 134 / 31 268 / 31 496 / 31
1 x P40: 4KiB Q1T1 19 / 1 35 / 1 61 / 1
Cost per month NZ$ 391.67 (Size 2TB)
       
1 x P60: Seq Q32T1 No read cache available
1 x P60: 4KiB Q8T8 No read cache available
1 x P60: 4KiB Q32T1 No read cache available
1 x P60: 4KiB Q1T1 No read cache available
Cost per month NZ$ 1,430.42 (Size 8TB)
       
1 x P70: Seq Q32T1 No read cache available
1 x P70: 4KiB Q8T8 No read cache available
1 x P70: 4KiB Q32T1 No read cache available
1 x P70: 4KiB Q1T1 No read cache available
Cost per month NZ$ 2,724.62 (Size 16TB)

There are a lot of ways to interpret the data above, but key findings included:

  • Host caching set to None, can offer faster performance than Read-only cache.
  • The Larger sized disks do not offer caching.
  • Good option for SQL Server when a low number of disks are allocated to the VM.

Host Caching set to Read/write

  E16-4s_v3 E32-8s_v3 E64-16s_v3
  Read / Write (MB/s) Read / Write (MB/s) Read / Write (MB/s)
1 x P30: Seq Q32T1 269 / 221 538 / 451 1080 / 792
1 x P30: 4KiB Q8T8 134 / 80 268 / 156 535 / 403
1 x P30: 4KiB Q32T1 134 / 87 269 / 117 470 / 239
1 x P30: 4KiB Q1T1 18 / 26 54 / 39 58 / 51
Cost per month NZ$ 204.37 (Size 1TB)
       
2 x P30: Seq Q32T1 269 / 270 538 / 440 1076 / 1077
2 x P30: 4KiB Q8T8 134 / 133 269 / 194 535 / 504
2 x P30: 4KiB Q32T1 133 / 134 269 / 127 489 / 388
2 x P30: 4KiB Q1T1 19 / 36 49 / 30 61 / 31
Cost per month NZ$ 408.74 (Size 2TB)
       
3 x P30: Seq Q32T1 269 / 270 539 / 535 1075 / 806
3 x P30: 4KiB Q8T8 134 / 129 268 / 266 535 / 524
3 x P30: 4KiB Q32T1 133 / 66 268 / 267 463 / 386
3 x P30: 4KiB Q1T1 19 / 24 49 / 45 58 / 41
Cost per month NZ$ 613.11 (Size 3TB)
       
4 x P30: Seq Q32T1 268 / 250 536 / 540 1070 / 1023
4 x P30: 4KiB Q8T8 134 / 68 267 / 202 536 / 530
4 x P30: 4KiB Q32T1 134 / 123 267 / 193 481 / 370
4 x P30: 4KiB Q1T1 19 / 27 49 / 44 60 / 40
Cost per month NZ$ 817.48 (Size 4TB)
       
5 x P30: Seq Q32T1 269 / 261 539 / 519 1070 / 1020
5 x P30: 4KiB Q8T8 134 / 133 268 / 267 536 / 531
5 x P30: 4KiB Q32T1 134 / 134 268 / 201 481 / 374
5 x P30: 4KiB Q1T1 19 / 39 49 / 38 60 / 41
Cost per month NZ$ 1,021.85 (Size 5TB)
       
1 x P40: Seq Q32T1 269 / 270 539 / 246 1079 / 993
1 x P40: 4KiB Q8T8 133 / 133 270 / 231 535 / 530
1 x P40: 4KiB Q32T1 133 / 71 268 / 55 484 / 409
1 x P40: 4KiB Q1T1 19 / 26 35 / 23 59 / 57
Cost per month NZ$ 391.67 (Size 2TB)
       
1 x P60: Seq Q32T1 No caching available
1 x P60: 4KiB Q8T8 No caching available
1 x P60: 4KiB Q32T1 No caching available
1 x P60: 4KiB Q1T1 No caching available
Cost per month NZ$ 1,430.42 (Size 8TB)
       
1 x P70: Seq Q32T1 No caching available
1 x P70: 4KiB Q8T8 No caching available
1 x P70: 4KiB Q32T1 No caching available
1 x P70: 4KiB Q1T1 No caching available
Cost per month NZ$ 2,724.62 (Size 16TB)
  • Microsoft does not recommend used of Read/write cache for SQL Server.

VM Temporary Drive

 

E16-4s_v3 (256GB Size)

E32-8s_v3 (512GB Size)

E64-16s_v3 (864GB Size)

  Read / Write (MB/s) Read / Write (MB/s) Read / Write (MB/s)
Seq Q32T1 270 / 270 538 / 535 1067 / 1074
4KiB Q8T8 134 / 134 268 / 266 476 / 489
4KiB Q32T1 133 / 133 248 / 238 277 / 271
4KiB Q1T1 15 / 22 20 / 29 21 / 30
  • The temporary drive throughput appears to reflect throttled premium disks with read/write cache enabled.

To summarize:

Review your VM’s temporary (D) drive performance and size to gauge where your tempdb database should be placed.

Having several striped disks does not guarantee that you will get faster throughput, rather this is dependent on the VM used.

To get faster IO performance you need a lot of disk space (even with the new Ultra disks), which you may / may not require, and remember you get charged for the whole storage (not just what you use) plus IOs (except temporary drive).

If you down scale a VM, you should ensure that the VM supports the number of drives you currently have attached and it you are using the temporary (D) drive, that the size will be sufficient for your tempdb files.

When using Storage Spaces, if you need to add additional capacity, you’ll need to add the same number of disks e.g. a 3 disk virtual drive will require an additional 3 disks. Also when the new disks are added, the Column count does not increase, so although you have increased capacity, you don’t increase the disk performance.

Depending on your SQL Server requirements, the cloud is not always cost effective.

tl;dr no cache enabled

Beware the impact of the ANSI_WARNINGS setting

Disabling the ANSI_WARNINGS setting in your code can compromise your data integrity.

As an example; say you are inserting an invoice number into a table and ANSI_WARNINGS are disabled.

Yay!

You pat yourself on the back as the insert succeeded.

Can you spot the issue?

Boo!

Ok you can take that pat back.

You should have ANSI_WARNINGS ON to ensure you get a warning and the operation doesn’t succeed.

Ahh!

One way to spot if an active connection has this setting disabled is to query the DMV sys.dm_exec_sessions. An example is shown below:

SELECT 
 session_id
,CASE WHEN [ansi_warnings] = 1 THEN 'yes' ELSE 'no' END AS is_ansi_warnings_enabled
FROM sys.dm_exec_sessions
WHERE session_id > 50;

Time to investigate session 54!

Check your SQL errorlog file sizes

At some stage you’ll likely want to check your SQL Server errorlog files using xp_readerrorlog or sp_readerrorlog.

If you haven’t worked on the server before and/or don’t have access to view the file sizes before running the command the below query will help obtain this information.

Why would you be interested in knowing the file sizes before running the command? Well, if the instance hasn’t been restarted in a while and sp_cycle_errorlog hasn’t been run, the log files could be really large and cause potential memory and IO performance issues when you try read them.

DECLARE @enumerrorlogs TABLE ([Log Type] varchar(5), [Archive #] int, [Date] datetime, [Log File Size (Byte)] bigint);

--get sql log file sizes
INSERT INTO @enumerrorlogs ([Archive #], [Date], [Log File Size (Byte)])
EXEC master.sys.sp_enumerrorlogs 1;

UPDATE @enumerrorlogs
SET [Log Type] = 'SQL'
WHERE [Log Type] IS NULL;

--get sql agent log file sizes
INSERT INTO @enumerrorlogs ([Archive #], [Date], [Log File Size (Byte)])
EXEC master.sys.sp_enumerrorlogs 2;

UPDATE @enumerrorlogs
SET [Log Type] = 'Agent'
WHERE [Log Type] IS NULL;

SELECT 
 a.[Log Type] AS log_type
,a.[Archive #] AS archive
,a.[Date] AS date_last_updated
,CAST(a.[Log File Size (Byte)]/1024/1024.0 AS decimal(20,3)) AS log_size_mb
FROM @enumerrorlogs a
ORDER BY a.[Log Type] DESC, a.[Archive #];

SQL Server 2014 Mainstream Support Gone

Yes SQL Server 2014 Mainstream Support ended this month. I didn’t notice much of a fuss. Possibly everyone is scrambling with SQL Server 2008/R2 exiting Extended Support or they are sorted.

That currently leaves SQL Server 2016 and SQL Server 2017 as the only mainstream products. SQL Server 2019 release is imminent, but uptake will likely take some time.

Warning: Clustered columnstore indexes on Azure SQL databases

If you are using clustered columnstore indexes on Azure SQL databases you run the risk of not being able to access your data when you change your pricing tier.

To demonstrate, I’ll create a basic table and add a Clustered columnstore index.

Simple table with CCI.

We’ll insert 2 rows and view the data.

2 rows added.

Let’s verify the current pricing tier.

We’re working with a S3.

Cool, we’ll change the database to a S2 to save some money.

Yay it’s now a S2.

The boss wants to view some data from that table we created earlier.

Bugger!

Now you know something to watch out for with CCIs.

Perform local backups and then save to Azure blob storage

Backing up your databases direct to Azure can be dangerous!

If you experience a router or network connectivity issue, then you run the risk of your transaction log backups consuming all disk space and halting your business operations.

If you start experiencing high network latency, then your backups could run into your business day and start impacting performance.

One solution is to perform a local backup and then load the backups into Azure. This way backups are not impacted by network outages/latency.

Let’s go through how this can be achieved.

The approach I’m using can also be used with SQL Server Express Edition.

Big caveat – these scripts were written in 1 day! Testing and error capture is minimal! Feel free to test and any feedback is welcome.

1. Prepare Your Azure Storage

Of course you can skip this step if you’ve got it setup already.

Create a Storage account.
You’ll be needing your Storage account name for later.
Enable Blob soft delete for a get out of jail free card.
Create and you’re nearly done.
Find your Storage account.
Go to Blobs.
Let’s create a Container (folder) to hold your SQL backups.
Give it a name and OK.
You’ll be needing that name later.
Right time to get your access keys!
Save your Key you’ll be needing it.

2. Get Your Favourite Ola Hallengren Backup Scripts

You’ll be wanting to save and deploy the shown 2 scripts on your SQL Server instance that you want to backup ref: https://ola.hallengren.com/downloads.html

Of course you can skip this step if you’ve got them already.

Deploy these to your SQL Server instance.
Yeah I created them in the master database, very naughty.

3. Create my sql_backups table in the same database

This table will keep track of your backups.

USE [master]
GO
CREATE TABLE [dbo].[sql_backups](
	[id] [bigint] IDENTITY(1,1) NOT NULL,
	[database_name] [nvarchar](128) NULL,
	[backup_type] [char](4) NULL,
	[backup_start_date] [datetime] NULL,
	[backup_end_date] [datetime] NULL,
	[local_backup_path] [nvarchar](4000) NULL,
	[keep_local_backup_hrs] [int] NULL,
	[local_backup_removed] [char](1) NULL,
	[local_backup_removed_date] [datetime] NULL,
	[saved_to_azure] [char](1) NULL,
	[azure_copy_start_date] [datetime] NULL,
	[azure_copy_end_date] [datetime] NULL,
	[azure_storage_account] [varchar](24) NULL,
	[azure_container] [varchar](64) NULL,
	[azure_backup_file] [nvarchar](4000) NULL,
	[keep_blob_backup_hrs] [int] NULL,
	[blob_backup_removed] [char](1) NULL,
	[blob_backup_removed_date] [datetime] NULL,
	[error_desc] [nvarchar](4000) NULL
) ON [PRIMARY]
GO
You should now see all 3 components.

4. Save PowerShell Backup and Copy Scripts

This solution makes use of 2 PowerShell scripts which can be scheduled using Task Scheduler or a SQL Server Agent job.

I’ve renamed the extension to txt in case you have issues on download.

SQL_Backups

SQL_Copy_Backups_To_Blob

The first script is SQL_Backups.ps1 and the second is SQL_Copy_Backups_To_Blob.ps1.

Simply save these to a folder of your choice.

PowerShell files you’ll be needing.

5. Schedule the SQL_Backups.ps1 Script

You would schedule SQL_Backups for Full and Log backups.

SQL_Backups.ps1 takes the following parameters and all are required:

  • instance – This is the instance which you’ll be backing-up e.g. ‘KN01\SQL2K19CTP3_0’
  • type – This is the standard Ola Hallengren backup types e.g. FULL or DIFF or LOG
  • local_backup_folder – This is where you want your local backups to go e.g. D:\SQLBackups
  • azure_storage_account – This is the Azure Storage account you created earlier e.g. sqlbackupsnz
  • azure_container – This is the Azure storage container (folder) you created earlier e.g. sqlbackups
  • keep_local_hrs – This is how many hours you would like to keep the local backups for e.g. 24
  • keep_blob_hrs – This is how many hours you would like to keep the blob backups for e.g. 168

An example of this running would be:

powershell –ExecutionPolicy Bypass -File C:\Scripts\SQL_Backups.ps1 -instance 'KN01\SQL2K19CTP3_0' -type 'FULL' -local_backup_folder 'D:\SQLBackups' -azure_storage_account 'sqlbackupsnz' -azure_container 'sqlbackups' -keep_local_hrs 24 -keep_blob_hrs 168

It just creates your standard local backups and populates the sql_backups table.

Saves backup details.
Showing other info stored.

Great so now you are secure from network issues/latency.

6. Schedule the SQL_Copy_Backups_To_Blob.ps1 Script

SQL_Copy_Backups_To_Blob.ps1 only needs to be scheduled once and typically it should run every 15 minutes.

This script checks and uploads local backups listed in the sql_backups table to Azure and will also check and remove local & blob backups which have passed your specified retention time.

Local backups that haven’t been uploaded to Azure won’t be deleted, even if their retention period has passed. Cool!

SQL_Copy_Backups_To_Blob.ps1 only has 1 parameter and it is required:

  • instance – This is the instance which you’ll be backing-up e.g. ‘KN01\SQL2K19CTP3_0’

What you will need to do is enter the Storage account and Key information that you created / viewed earlier. This allows the backups to be uploaded and blobs to be removed.

NOTE: This is in 2 places in the file, yeah lazy scripting.

Set you Storage connection information. Yikes it’s not encrypted! O’well at least your server is locked down!

An example of this running would be:

powershell –ExecutionPolicy Bypass -File C:\Scripts\SQL_Copy_Backups_To_Blob.ps1 -instance 'KN01\SQL2K19CTP3_0'
sql_backups table updated.
Back in Azure, you’ll see your backups.

That is it, when backups / blobs exceed your hours to keep threshold, they will be removed.

Enjoy!

SQL Server Supported Upgrade Paths

In-place upgrade paths of SQL Server are shown below.

Ahh the memories

Note: You’ll need to take into consideration:

Destination
2008

2008 R2

2012

2014

2016

2017

2019*
Source
2005
122
20083 455
2008 R26 7 8 8
20129 10 10
2014
2016
2017

1 Minimum SQL Server 2005 SP2

2 Minimum SQL Server 2005 SP4

3 Minimum SQL Server 2008 SP2

4 Minimum SQL Server 2008 SP3

5 Minimum SQL Server 2008 SP4

6 Minimum SQL Server 2008 R2 SP1

7 Minimum SQL Server 2008 R2 SP2

8 Minimum SQL Server 2008 R2 SP3

9 Minimum SQL Server 2012 SP1

10 Minimum SQL Server 2012 SP2

*  Unknown at this stage but SQL Server 2008 and SQL Server 2008 R2 are not blocked